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Biomedical subjects

Z Wu

Publications and source records attributed to Z Wu.

At least 685 records · Page 38Linked to original sources
PubMed1994

[Investigation on HBV-M among hospital workers and observation on the efficacy of vaccination against type B hepatitis].

An epidemiological study on HBV infection among 315 staff of PUMC Hospital was carried out with detection of HBsAg, anti-HBs and anti-HBc by ELISA. The results showed that 138 persons had one or more markers of HBV infection and an overall HBV prevalence rate 43.8%. The positive rates of HBsAg anti-HBs, anti-HBc were 6.3%, 28.9% and 8.6%, respectively. This indicates that HBV infection is a risk factor for medical staff, but there was no significant difference among medical, surgical and other members. In 1992, 177 workers whose HBV markers were negative received 3 doses of HB vaccine at 0, 1 and 6 months, respectively. 91.3 percent of them showed an anti-HBs response one month after the last inoculation. The result shows that our national made HB vaccine is safe and immunogenic.

Adult↗
PubMed1994

[Clinicopathological analysis of rhabdomyosarcoma of the ocular adenexa].

12 cases including 11 males and 1 female of rhabdomyosarcoma of ocular adenexa were analysed. The average age of the patients was 4.2 years. 9 cases of lesion were located in the orbit, 2 in the eyelid and 1 in conjunctiva. Pathologically 8 cases were embryonal forms, 2 alveolar, 2 polymorphic. Immunohistochemical studies were performed in 8 cases, which showed desmin positive. Myoglobin presented strong or weak positive in 5 cases, suspicious positive in 3 cases. The clinical manifestation, prognosis and treatment were briefly discussed.

Child↗
PubMed1994

Ultrastructural study of the hemopoietic microenvironment in human fetal spleen.

Reciprocal interactions between hemopoietic stromal cells and immature hemopoietic cells in human spleens obtained from 20 fetuses of 10-28 weeks gestation were observed by transmission electron microscopy and scanning electron microscopy. The close association of stromal cells with immature hemopoietic cells was confirmed under the electron microscope and a presumptive HIM (Hemopoietic inductive microenvironment) was visualized. In regions of immature hemopoietic cell-reticular cell, endothelial cell, macrophage and interdigitating cell contact, some communicating structures were found between the plasma membranes of adjacent cells; moreover, the cytoplasm of these four stromal cells were full of various kinds of organelles. These results suggest that reticular cells, endothelial cells, macrophages and interdigitating cells are component parts of the HIM of human fetal spleen and that these cells have a nurturing function in relation to hemopoietic cells.

Animals↗
PubMed1994

[A case-control study on risk factors in etiology of Parkinson's disease].

Risk factors of Parkinson's disease (PD) were studied by the case-control method (1:1) in 90 cases. It was suggested that the high positive rate (34.4%) in PD family history was related to "genetic susceptibility". There was history of head injury, rheumatic fever, seizure, taking anti-psychosis drug or contact with toxins, but any one factor could not completely explain the etiology of PD. We believe that coordinating effects of both susceptibility in genetics and environmental toxins may explain the mechanism of PD.

Aged↗
PubMed1993

Modification of the calcium and calmodulin sensitivity of the type I adenylyl cyclase by mutagenesis of its calmodulin binding domain.

The type I adenylyl cyclase is directly stimulated by Ca2+ and calmodulin in vitro, and the enzyme is also stimulated by increases in intracellular Ca2+ in vivo. Ca2+ stimulation of the enzyme in vivo may be due to direct interactions of the enzyme with Ca2+ and calmodulin or to an indirect mechanism involving stimulation of the enzyme by Ca(2+)-activated protein kinases. In this study, we have made several point mutations within the calmodulin binding domain to determine if the Ca2+ sensitivity of the enzyme can be modified by mutagenesis. The catalytic activities of the mutant enzymes were comparable to wild type type I adenylyl cyclase. Substitution of Cys-507 with Ser-507 did not have significant effects on the calmodulin or Ca2+ sensitivity of the enzyme. However, replacement of Lys-504 with Asp caused a 4-fold decrease in sensitivity to Ca2+. Ca2+ and calmodulin stimulation were abolished by substitution of Phe-503 with Arg-503. Stimulation of type I adenylyl cyclase activity in vivo by intracellular Ca2+ was also greatly diminished with the Arg-503 mutant indicating that Ca2+ stimulation of the enzyme in vivo is due primarily to direct interactions with calmodulin and Ca2+. These data demonstrate that the Ca2+ sensitivity of this enzyme can be modulated by point mutagenesis within the putative calmodulin binding domain and indicate that the enzyme can be directly regulated by Ca2+ and calmodulin in vivo.

Adenylyl Cyclases↗
PubMed1993

Overexpression in Escherichia coli of soluble aristolochene synthase from Penicillium roqueforti.

Aristolochene synthase, a fungal cyclase which has been isolated from Aspergillus terreus and Penicillium roqueforti, catalyzes the cyclization of farnesyl diphosphate to the sesquiterpene hydrocarbon aristolochene. The aristolochene synthase gene (Ari1) of P. roqueforti has previously been cloned and expressed at low levels as a protein A-aristolochene synthase fusion protein in Escherichia coli. We have now used the polymerase chain reaction to amplify the aristolochene synthase coding sequence using engineered primers which produced dsDNA carrying an EcoRI restriction site and the T7 gene 10 ribosome binding site and translational spacer element immediately upstream of the ATG start codon and a BamHI site adjacent to the TAA stop codon. The PCR product was digested with EcoRI and BamHI and inserted into the multiple cloning site of the expression vector pLM1 which carried the promoter and translational leader sequence from T7 gene 10 and the E. coli rrnBT1T2 tandem transcription terminator. Cloning of the resulting construct into E. coli XL1-Blue and subcloning into the expression host E. coli BL21 (DE3) gave transformants which expressed aristolochene synthase at levels up to 40% of soluble protein when induced with isopropyl beta-D-thiogalactoside. Purification of the recombinant protein by ammonium sulfate precipitation, ion-exchange chromatography on Q Sepharose, and affinity dye chromatography on Reactive Blue 4-agarose gave homogenous aristolochene synthase which had the expected N-terminal sequence, ATSTE, mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and steady-state kinetic parameters when compared to native fungal protein.

Base Sequence↗
PubMed1993

Fast minimicroassay of serum retinol (vitamin A) by capillary zone electrophoresis with laser-excited fluorescence detection.

In this paper, we present a fast minimicroassay of serum vitamin A by capillary zone electrophoresis with laser-excited fluorescence detection. A 60 cm x 50 microns I.D. fused-silica capillary was used for the separation, and the polymer coating was burned off 20 cm from the cathodic end to form a detection window. The buffer system consisted of 50 mM sodium phosphate plus 10 mM sodium chloride at pH 7.8. A helium-cadmium laser set at 325 nm was used for excitation, and the fluorescence of the vitamin A-retinol-binding protein complex was monitored at 465 nm using a photodiode. The stray and scattered radiation were removed by two special filters. Using this system, about 8 nl of serum sample were injected for direct analysis without any sample preparation. The analysis time for each sample was less than 6 min, and subfemtomole levels of vitamin A in human or animal blood could be easily detected. Therefore, the method is potentially useful for finger-prick vitamin A analysis, especially for babies and young children.

Buffers↗
PubMed1993

Forward-scattering degenerate four-wave mixing as a simple sub-attomole-sensitive nonlinear laser analytical spectrometric method.

Optical phase conjugation by "forward-scattering" degenerate four-wave mixing in an absorbing liquid analyte solution is reported as a sensitive and simple nonlinear laser spectroscopic method. Since only two input laser beams are used in this nonlinear four-wave mixing setup, it offers important advantages including ease of optical alignment, efficient use of input photon density, low laser power requirements, and high wave-mixing efficiency. In addition, since the phase-conjugate signal is a laser beam, optical signal detection is very efficient and the signal-to-noise is excellent. Important characteristics of this novel nonlinear laser technique, including signal dependence on analyte concentration, individual input beam power, and modulation frequencies, are examined. Excellent detection sensitivity, small detection volume, and convenient sample introduction promise many applications for this nonlinear laser spectroscopic method. Preliminary detection limits of 0.7 amol of eosin B and 45 amol of iodine inside a probe volume of 98 pL are reported using a forward-scattering degenerate four-wave mixing setup.

Lasers↗
PubMed1993

Estimating historical exposure to silica among mine and pottery workers in the People's Republic of China.

A quantitative retrospective exposure assessment method was developed for use in a nested case-control study of lung cancer among mine and pottery workers exposed to silica dust in the People's Republic of China. Exposure assessment was carried out in 20 mines (10 tungsten, 6 iron/copper, and 4 tin) and nine pottery factories. A job title dictionary was developed and used in both the collection of historical exposure information and work histories of 1,668 (316 cases and 1,352 controls) study subjects. Several data abstraction forms were developed to collect historical and current exposure information and employees' work histories, starting in 1950. A retrospective exposure matrix was developed on the basis of facility/job title/calendar year combinations using available historical exposure information and current exposure profiles. Information on the amount of respirable, thoracic, and free silica content in total dust was used in estimating exposure to silica. Starting in 1950, 6,805 historical estimates had been carried out for 14 calendar-year periods. We estimated the average total dust concentration to be 9 mg/M3, with a range from 28 mg/M3 in earlier years to 3 mg/M3 in recent years. Several exposure indices [such as cumulative dust, average dust, cumulative respirable (< 5 mu in particle size) and thoracic (< 10 mu in particle size) silica dust, average respirable and thoracic silica dust, exposure-weighted duration, and the highest/longest exposure] were calculated for individuals by merging work history and historical exposure matrix for each study subject. We developed these various measures of exposure to allow investigators to compare and contrast different indices of historical exposure to silica.

Case-Control Studies↗
PubMed1993

Kinetic and DNA-binding properties of recombinant human O6-methylguanine-DNA methyltransferase.

O6-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair protein that plays an important role in chemotherapy, mutagenesis, and carcinogenesis. Recombinant human MGMT was isolated from an Escherichia coli high performance expression system and purified to homogeneity. The kinetic and DNA-binding properties of the recombinant human MGMT were studied. The purified human MGMT reacted stoichiometrically with methylated DNA under second-order rate kinetics. The rate constant with normal methylated DNA was 1 x 10(9) M-1 min-1 at 37 degrees C. The binding to DNA was the rate determining step in the repair process. Approximately eight base pairs of the DNA substrate were covered by the human MGMT protein. The affinity constant for interaction of DNA to MGMT was approximately 4.7 x 10(5) M-1. The binding to methylated DNA was also examined; the binding affinity to methylated DNA was two times higher than that to unmodified DNA. The interaction with DNA induced a conformational change in the human MGMT protein as monitored by circular dichroism and fluorescence analysis. A similar conformational change was induced by both methylated and unmodified DNA.

Base Sequence↗
PubMed1993

Overproduction of soluble trichodiene synthase from Fusarium sporotrichioides in Escherichia coli.

Trichodiene synthase is a sesquiterpene cyclase isolated from various fungal species which catalyzes the cyclization of farnesyl diphosphate (FPP) to trichodiene. The trichodiene synthase gene (Tox5) of Fusarium sporotrichioides has previously been cloned and expressed as 0.05-0.1% of total cell protein in Escherichia coli. We have used polymerase chain reaction to amplify the trichodiene coding sequence carried on the plasmid pTS56-1. The resulting DNA, carrying a BamHI restriction site and the T7 gene 10 ribosome binding site and translational spacer element immediately upstream of the ATG start codon as well as a HindIII site adjacent to the translational stop codon, was inserted into the corresponding sites of the expression vector pLM1. The latter vector carried the promoter and translational leader sequence from T7 gene 10 and the E. coli rmBT1T2 tandem transcription terminator. This construct was cloned into E. coli BL21 (DE3). The resulting transformants, when induced with isopropyl beta-D-thiogalactoside, produced trichodiene synthase as 20-30% of total soluble protein. The recombinant synthase, which could be purified five-fold to homogeneity by ammonium sulfate precipitation, ion-exchange chromatography on Q Sepharose, and gel filtration on Superose 12, was identical to native protein in steady-state kinetic parameters and mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and had the expected MENFP N-terminal sequence.

Base Sequence↗
PubMed1993

Factors contributing to reinfection with schistosomiasis japonica after treatment in the lake region of China.

The prevalence of schistosomiasis due to S. japonicum is focally high in the lake regions of China, and reinfection after treatment with praziquantel is frequent. In this study, the total reinfection rate among 740 treated persons was 12.9%. Factors associated with reinfection were age and sex, water contact and the distance from homes to snail habitats. The reinfection rate was higher among men (15.0%) than among women (8.3%). The frequency of water contact is the main factor in reinfection. Among persons with more than 120 and 10-120 water-contact days, the reinfection rates were 24.0% and 16.4%, respectively. The reinfection rates among people living 0 m, 500 m and 1000 m from snail-ridden areas were 14.1%, 8.3% and 4.3%, respectively. Fishing was the most frequent reason for water-contact, followed by herding animals and playing in water; reinfection rates among those engaging in these activities were 36.4%, 16.3% and 22.9%, respectively. Reinfection is clearly a problem, and since much of it is connected with essential economic activities, the cycle of infection and reinfection is not likely to be broken until effective methods for eliminating reservoirs of infection are developed.

Adolescent↗
PubMed1993

An evaluation of the renal protective effect of manidipine in the uninephrectomized spontaneously hypertensive rat.

The effects of calcium antagonism on the development and progression of renal disease are controversial. To address this problem, studies were performed on young, uninephrectomized spontaneously hypertensive rats (SHRs) with the dihydropyridine calcium antagonist, manidipine, to assess its effect on the early pathogenesis of focal glomerulosclerosis. Male SHRs underwent uninephrectomy at age 10 to 11 weeks and were subsequently assigned to no treatment (control), a predetermined subvasodepressor (low) dose of manidipine (2.5 mg/kg body weight), or a predetermined antihypertensive (high) dose of manidipine (20 mg/kg body weight). All animals received a diet containing 0.4% sodium and 23% protein. Serial determinations of body weight, systolic tail cuff pressure, and 24-hour urinary excretion of creatinine, sodium, and protein (UprotV) were made at 1- to 6-week intervals, for a total treatment period of 12 weeks. In final experiments plasma was obtained for creatinine, angiotensin I, and angiotensin II determinations, and renal tissue was harvested for histologic and morphometric analysis. Compared with the untreated control, low-dose manidipine therapy had no effect on body weight, systolic blood pressure, creatinine clearance, UprotV, renal histologic findings, glomerular volume, or plasma angiotensin I or II concentrations. In contrast, high-dose manidipine therapy decreased systolic blood pressure from 194 +/- 3 to 160 +/- 4 mm Hg (p < 0.01). Creatinine clearance and UprotV were unchanged. Although body weight was not different, kidney weight was higher. However, mean glomerular volume was lower. More importantly, the prevalence of mesangial expansion with proliferation was lower: 6.7% (control) versus 2.8% (high-dose manidipine) (p < 0.01). Finally, plasma angiotensin I and angiotensin II concentrations did not differ.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1993

Renal tissue angiotensin II: response to infusions of angiotensin I and an angiotensin-converting enzyme inhibitor.

A procedure for the collection, processing, extraction, separation, and measurement of renal tissue angiotensin II [ANG-(1-8)] is described. The arterial plasma and renal tissue concentrations of ANG-(1-8) were examined in anesthetized Sprague-Dawley male rats (10 to 12 weeks of age) given an intravenous saline infusion (group 1; n = 6), an intravenous bolus infusion of 0.5 microgram angiotensin I (group 2; n = 6), or an intravenous bolus of an angiotensin-converting enzyme inhibitor (group 3; n = 6). Plasma and renal tissue were collected at the peak mean arterial pressure (MAP) response. The mean (+/- SEM) concentration of ANG-(1-8) in the group given the saline vehicle was 12 +/- 2 fmol/mL in the plasma and 2.4 +/- 0.3 pmol/g in the renal tissue. The angiotensin I bolus significantly increased MAP by 40%. Following the angiotensin I infusion, at the time of peak MAP response, the concentration of the circulating and renal tissue ANG-(1-8) were 12-fold and twofold higher, respectively, compared with the saline vehicle. The angiotensin-converting enzyme inhibitor significantly decreased MAP by 10% and decreased the circulating and renal tissue ANG-(1-8) levels by 75% and 62.5%, respectively, compared with the saline vehicle. The rapid conversion of exogenous angiotensin I to ANG-(1-8) in renal tissue provides direct evidence that renal tissue can generate de novo ANG-(1-8) from a circulating precursor. Furthermore, plasma and renal tissue respond similarly to acute angiotensin-converting enzyme inhibition.

Angiotensin I↗
PubMed1993

Snurposomes and coiled bodies.

In the GV of amphibian oocytes, the splicing snRNPs (U1, U2, U4, U5, and U6) occur on most of the lampbrush chromosome loops in association with the nascent transcripts. They also occur in thousands of small extrachromosomal bodies (1-4 microns in diameter) designated B snurposomes. U7 snRNA, which is involved in processing the 3' end of histone pre-mRNAs, occurs in a few dozen extrachromosomal bodies (1-20 microns in diameter) called C snurposomes. C snurposomes often have B snurposomes attached to their surface and B-like inclusions; these compound structures are known as spheres or sphere organelles. One or two sphere organelles are attached to the lampbrush chromosomes at the histone gene loci. Two snRNAs (or snoRNAs) known to be involved in pre-rRNA processing (U3 and U8) occur in the 1000 or so extrachromosomal nucleoli of the GV. We looked for a snurposome that might contain U3 and U8 but not rDNA or rRNA. We were unable to find such a snurposome, but we did identify a hitherto unrecognized population of minute nucleoli in the size range of B snurposomes. Prenucleolar bodies in telophase/early interphase nuclei meet the definition of a pre-rRNA snurposome in that they contain U3 snoRNA and fibrillarin (and probably other processing components) but lack rDNA and do not synthesize rRNA. The structures previously identified as prenucleolar bodies in pronuclei formed in vitro in Xenopus egg extracts share many components with coiled bodies from HeLa nuclei.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗